Hybrid systems and methods for low-latency user input processing and feedback

ABSTRACT

A system for processing user input includes an input device, an input processing unit, a high-latency subsystem, a low-latency subsystem, input processing unit software for generating signals in response to user inputs, and an output device. The low-latency subsystem receives the signals and generates low-latency output and the high-latency subsystem processes the signals and generates high-latency output.

This application is a non-provisional of and claims priority to U.S.Provisional Patent Application No. 61/710,256 filed Oct. 5, 2012entitled “Hybrid Systems And Methods For Low-Latency User InputProcessing And Feedback,” the entire disclosure of which, including thesource code appendix thereto, is incorporated herein by reference in itsentirety.

This application includes material which is subject to copyrightprotection. The copyright owner has no objection to the facsimilereproduction by anyone of the patent disclosure, as it appears in thePatent and Trademark Office files or records, but otherwise reserves allcopyright rights whatsoever.

FIELD

The present invention relates in general to the field of user input, andin particular to user input systems which deliver a low-latency userexperience.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of thedisclosure will be apparent from the following more particulardescription of embodiments as illustrated in the accompanying drawings,in which reference characters refer to the same parts throughout thevarious views. The drawings are not necessarily to scale, emphasisinstead being placed upon illustrating principles of the disclosedembodiments.

FIG. 1 illustrates a demonstration of the effect of drag latency at 100ms, 50 ms, 10 ms, and 1 ms in a touch user interface.

FIG. 2 shows an example of a user interface element for an inbox, wherethe element has a low latency, low fidelity response to a touch userinteraction, as well as a high-latency, high-fidelity response a touchuser interaction.

FIG. 3 shows an example of a user interface of a sliding toggle element.A cursor 310 (represented by the box containing a “cross” character) canbe dragged to the target 320 (second empty box, on the right) toactivate the UI Element. This element is enabled using both the lowlatency and high-latency system to provide a touch interaction wheremoving elements are accelerated 310, thus providing a low-latencyexperience.

FIG. 4 shows an illustrative embodiment of a basic architecture of aprototype high-performance touch system used in latency perceptionstudies.

FIG. 5 shows results of latency perception studies using the prototypedevice of FIG. 4.

FIG. 6 shows an example of a user interface element for a button, wherethe element has a low latency, low fidelity response to a touch userinteraction, as well as a high-latency, high-fidelity response a touchuser interaction.

FIG. 7 shows an example of a user interface element for resizable box,where the element has a low latency, low fidelity response to a touchuser interaction, as well as a high-latency, high-fidelity response atouch user interaction.

FIG. 8 shows an example of a user interface element for a scrollablelist, where the element has a low latency, low fidelity response to atouch user interaction, as well as a high-latency, high-fidelityresponse to a touch user interaction.

FIG. 9 shows an illustrative embodiment of a basic architecture andinformation flow for a low-latency input device.

FIG. 10 shows the UI for a volume control. When dragging the slider, atooltip appears showing a numeric representation of the current setting.This element is enabled using both the low-latency and high-latencysystem to provide a touch interaction where moving elements areaccelerated, thus providing a low-latency experience.

FIG. 11 shows the system's response for pen input in prior art systemscompared to an embodiment of the UI for pen input in the present hybridfeedback user interface system. In the hybrid system, the ink stroke hasa low-latency response to pen input, as well as a high-latency responseto a pen user input.

FIG. 12 shows an embodiment of the system where data flows through twooverlapping paths through the components of the system to support bothhigh- and low-latency feedback.

FIG. 13 shows a programming paradigm well known in the art called ModelView Controller.

FIG. 14 shows an embodiment of the system's architecture that supportsdeveloping and running applications with blended high and low-latencyresponses to user input.

DETAILED DESCRIPTION

The following description and drawings are illustrative and are not tobe construed as limiting. Numerous specific details are described toprovide a thorough understanding. However, in certain instances,well-known or conventional details are not described in order to avoidobscuring the description. References to one or an embodiment in thepresent disclosure are not necessarily references to the sameembodiment; and, such references mean at least one.

Reference in this specification to “one embodiment” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least one embodimentof the disclosure. The appearances of the phrase “in one embodiment” invarious places in the specification are not necessarily all referring tothe same embodiment, nor are separate or alternative embodimentsmutually exclusive of other embodiments. Moreover, various features aredescribed which may be exhibited by some embodiments and not by others.Similarly, various requirements are described which may be requirementsfor some embodiments but not other embodiments.

Overview

This application relates to user interfaces such as the fast multi-touchsensors and other interfaces disclosed in U.S. patent application Ser.No. 13/841,436 filed Mar. 15, 2013 entitled “Low-Latency Touch SensitiveDevice,” U.S. Patent Application No. 61/798,948 filed Mar. 15, 2013entitled “Fast Multi-Touch Stylus,” U.S. Patent Application No.61/799,035 filed Mar. 15, 2013 entitled “Fast Multi-Touch Sensor WithUser-Identification Techniques,” U.S. Patent Application No. 61/798,828filed Mar. 15, 2013 entitled “Fast Multi-Touch Noise Reduction,” U.S.Patent Application No. 61/798,708 filed Mar. 15, 2013 entitled “ActiveOptical Stylus,” U.S. Patent Application No. 61/710,256 filed Oct. 5,2012 entitled “Hybrid Systems And Methods For Low-Latency User InputProcessing And Feedback,” U.S. Patent Application No. 61/845,892 filedJul. 12, 2013 entitled “Fast Multi-Touch Post Processing,” U.S. PatentApplication No. 61/845,879 filed Jul. 12, 2013 entitled “ReducingControl Response Latency With Defined Cross-Control Behavior,” and U.S.Patent Application No. 61/879,245 filed Sep. 18, 2013 entitled “SystemsAnd Methods For Providing Response To User Input Using Information AboutState Changes And Predicting Future User Input.” The entire disclosuresof those applications are incorporated herein by reference.

In various embodiments, the present disclosure is directed to systemsand methods that provide direct manipulation user interfaces with lowlatency. Direct physical manipulation of pseudo “real world” objects isa common user interface metaphor employed for many types of inputdevices, such as those enabling direct-touch input, stylus input, in-airgesture input, as well as indirect devices, including mice, trackpads,pen tablets, etc. For the purposes of the present disclosure, latency ina user interface refers to the time it takes for the user to bepresented with a response to a physical input action. Tests have shownthat users prefer low latencies and that users can reliably perceivelatency as low as 5-10 ms, as will be discussed in greater detail below.

FIG. 1 illustrates a demonstration of the effect of latency in anexemplary touch user interface at 100 ms (ref. no. 110), 50 ms (ref. no.120), 10 ms (ref. no. 130), and 1 ms (ref. no. 140) respectively. Whendragging an object, increasing latency is reflected as an increasingdistance between the user's finger and the object being dragged (in thiscase a square user interface element). As can be seen, the effects oflatency are pronounced at 100 ms (ref. no. 110) and 50 ms (ref no. 120),but become progressively less significant at 10 ms (ref no. 130), andvirtually vanish at 1 ms (ref. no. 140). FIG. 11 illustrates the effectsof latency in an exemplary stylus or pen user interface (1110, 1120). Inthis example, lag 1120 is visible as an increasing distance between thestylus 1100 tip and the computed stroke 1110. With the introduction oflow-latency systems, the distance between the stylus 1100 tip and thecomputed stroke 1130 would be significantly reduced.

In an embodiment, the presently disclosed systems and methods provide ahybrid touch user interface that provides immediate visual feedback witha latency of less than 10 ms, inter-woven or overlayed with additionalvisual responses at higher levels of latency. In some embodiments, thedesigns of these two sets of responses may be designed to be visuallyunified, so that the user is unable to distinguish them. In someembodiments, the “low latency” response may exceed 10 ms in latency.

Causes of Latency

In various embodiments, latency in a user input device and the systemprocessing its input can have many sources, including:

-   (1) the physical sensor that captures touch events;-   (2) the software that processes touch events and generates output    for the display;-   (3) the display itself;-   (4) Data transmission between components, including bus;-   (5) Data internal storage in either memory stores or short buffers;-   (6) Interrupts and competition for system resources;-   (7) Other sources of circuitry can introduce latency;-   (8) Physical restrictions, such as the speed of light, and its    repercussions in circuitry architecture.-   (9) Mechanical restrictions, such as the time required for a    resistive touch sensor to bend back to its ‘neutral’ state.

In various embodiments, reducing system latency can be addressed throughimproving latency in one or more of these components. In an embodiment,the presently disclosed systems and methods provide an input device thatmay achieve 1 ms of latency or less by combining a low-latency inputsensor and display with a dedicated processing system. In an embodiment,the presently disclosed systems and methods provide an input device thatmay achieve 5 ms of latency or less by combining such low-latency inputsensor and display with a dedicated processing system. In a furtherembodiment, the presently disclosed systems and methods provide an inputdevice that may achieve 0.1 ms of latency or less by combining suchlow-latency input sensor and display with a dedicated processing system.In a further embodiment, the presently disclosed systems and methodsprovide an input device that may achieve 10 ms of latency or less bycombining such low-latency input sensor and display with a dedicatedprocessing system. In an embodiment, in order to achieve such extremelylow latencies, the presently disclosed systems and methods may replaceconventional operating system (OS) software and computing hardware witha dedicated, custom-programmed field programmable gate array (FPGA) orapplication-specific integrated circuit (ASIC). In an embodiment, theFPGA or ASIC replaces the conventional OS and computing hardware toprovide a low latency response, while leaving a traditional OS andcomputing hardware in place to provide a higher latency response (whichis used in addition in addition to the low latency response). In anotherembodiment, some or all of the function of the FPGA or ASIC describedmay be replaced by integrating additional logic into existing componentssuch as but not limited to the graphics processing unit (GPU), inputdevice controller, central processing unit (CPU), or system on a chip(SoC). The low-latency logic can be encoded in hardware, or in softwarestored-in and/or executed by those or other components. In embodimentswhere multiple components are required, communication and/orsynchronization may be facilitated by the use of shared memory. In anyof these embodiments, responses provided at high or low latency may beblended together, or only one or the other might be provided in responseto any given input event.

In various embodiments, the disclosed systems and methods provide whatis referred to herein as “hybrid feedback.” In a hybrid feedback system,some of the basic system responses to input are logically separated fromthe broader application logic. The result provides a system with animble input processor, capable of providing nearly immediate systemfeedback to user input events, with more feedback based on applicationlogic provided at traditional levels of latency. In some embodiments,these system responses are provided visually. In various embodiments,the low-latency component of a hybrid feedback system may be providedthrough audio or vibro-tactile feedback. In some embodiments, the nearlyimmediate feedback might be provided in the same modality as theapplication-logic feedback. In some embodiments, low-latency feedbackmay be provided in different modalities, or multiple modalities. Anexample of an all-visual embodiment is shown in FIG. 2, in this caseshowing the use of a touch input device. In particular, FIG. 2 shows theresult after a user has touched and then dragged an icon 210representing an inbox. When the user touches the icon 210, a border 220or other suitable primitive may be displayed. In an embodiment, in anall-visual low-latency feedback, a suitable low-fidelity representationmay be selected due to its ease of rendering. In an embodiment, alow-latency feedback may be provided using one or more primitives thatcan provide a suitable low-fidelity representation. In an embodiment, ifthe user drags the icon to another place on the touch display 200, a lowfidelity border 230 is displayed and may be manipulated (e.g., moved)with a low latency of, for example, 1 ms. Simultaneously, the movementof the icon 210 may be shown with higher latency. In an embodiment, thedifference in response between the nearly immediate low-latency responseand the likely slower application-logic feedback can be perceived by auser. In another embodiment, this difference in response between thelow-latency response and a traditional response is blended and lessnoticeable or not noticeable to a user. In an embodiment, the nearlyimmediate feedback may be provided at a lower fidelity than thetraditional-path application-logic feedback. In an embodiment, in atleast some cases, the low latency response may be provided at similar oreven higher fidelity than the application-logic feedback. In anembodiment, the form of low-latency nearly immediate feedback isdictated by application logic, or logic present in the system software(such as the user interface toolkit). For example, in an embodiment,application logic may pre-render a variety of graphical primitives thatcan then be used by a low-latency subsystem. Similarly, in anembodiment, a software toolkit may provide the means to developgraphical primitives that can be rendered in advance of being needed bythe low latency system. In an embodiment, low-latency responses may bepredetermined, or otherwise determined without regard to applicationand/or system software logic. In an embodiment, individual pre-renderedor partially rendered low-latency responses, or packages of pre-renderedor partially rendered low-latency responses can be pre-loaded into amemory so as to be accessible to the low-latency subsystem in advance ofbeing needed for use in response to a user input event.

In an embodiment, the modality of low-latency output might be auditory.In an embodiment, the low-latency system may be used, for example, tosend microphone input quickly to the audio output system, which mayprovide users with an “echo” of their own voice being spoken into thesystem. Such a low-latency output may provide the impression of havingthe same type of echo characteristics as traditional analog telephones,which allow a user to hear their own voice. In an embodiment,low-latency auditory feedback might be provided in response to userinput events (e.g., touch, gesture, pen input, oe oral inputs), with ahigher latency response provided visually.

Another illustrative embodiment of a system that employs the presentmethod and system is shown in FIG. 3. In the illustrative system, acursor 310 (represented by the box containing a “cross” character) canbe dragged anywhere on a device's screen 300. When cursor 310 is draggedto target box 320, the UI action is accepted. If the cursor 310 isdragged elsewhere on the screen 300, the action is rejected. In anembodiment, when dragged, the cursor 310 is drawn with low latency, andthus tracks the user's finger without perceptible latency. In anembodiment, the target 320 can be drawn with higher latency withoutimpacting user perception. Similarly, in an embodiment, the response 330of “REJECT” or “ACCEPT” may occur perceptibly later, and thus it can bedrawn at a higher latency, e.g., not using the low latency subsystem,without impacting user perception.

It should be understood that the illustrated embodiment is exemplary.The principles illustrated in FIG. 3 may be applied to any kind of UIelement, including all UI elements that are now known, or laterdeveloped in the art. Similarly, the principals illustrated in FIG. 3can be used with substantially any kind of input event on various typesof input devices and/or output devices. For example, in an embodiment,in addition to a “touch” event as illustrated above, input events caninclude, without limitation, in-air or on-surface gestures, speech,voluntary (or involuntary eye movement, and pen. In an embodiment, oncea gesture takes place, the response of any UI element may be bifurcated,where a low-latency response (e.g., a low-fidelity representation of aUI element is presented and responds quickly, for example, in 0.01 ms.),and a non-low-latency response (e.g., a further refined representationof the UI element) is provided with latency commonly exhibited by asystem that does not provide accelerated input. In an embodiment,responses may not be split in a hybrid system, and may instead beentirely low latency, with application logic not responsible for thelow-latency response otherwise executing with higher latency.

In an embodiment, touch and/or gesture input events can be achievedusing a variety of technologies, including, without limitation,resistive, direct illumination, frustrated total-internal reflection,diffuse illumination, projected capacitive, capacitive coupling,acoustic wave, and sensor-in-pixel. In an embodiment, pen input can beenabled using resistive, visual, capacitive, magnetic, infrared, opticalimaging, dispersive signal, acoustic pulse, or other techniques. In anembodiment, gestural input may also be enabled using visual sensors orhandheld objects (including those containing sensors, and those usedsimply for tracking), or without handheld objects, such as with 2D and3D sensors. Combinations of the sensors or techniques for identifyinginput events are also contemplated, as are combinations of event types(i.e., touch, pen, gesture, retina movement, etc.) One propertytechnologies to identify or capture input events share is that theycontribute to the latency between user action and the system's responseto that action. The scale of this contribution varies acrosstechnologies and implementations.

In a typical multitouch system, there is a path of information flowbetween the input device and the display that may involvecommunications, the operating system, UI toolkits, the applicationlayer, and/or ultimately, the audio or graphics controller. Each ofthese can add latency. Moreover, latency introduced by an operatingsystem, especially a non-real time operating system, is variable.Windows, iOS, OSX, Android, etc. are not real time operating systems,and thus, using these operating systems, there is no guarantee that aresponse will happen within a certain time period. If the processor isheavily loaded, for example, latency may increase dramatically. Further,some operations are handled at a very low level in the software stackand have high priority. For example, the mouse pointer is typicallyhighly optimized so that even when the processor is under heavy load,the perceived latency is relatively low. In contrast, an operation suchas resizing a photo with two fingers on a touch or gestural system isgenerally much more computationally intensive as it may require constantrescaling of the image at the application and/or UI toolkit levels. As aresult, such operations are rarely able to have a low perceived latencywhen the processor is under heavy load.

In a typical multitouch system, the display system (including thegraphics system as well as the display itself) may also contribute tolatency. Systems with high frame rates may obscure the actual latencythrough the system. For example, a 60 Hz monitor may include one or moreframes of buffer in order to allow for sophisticated image processingeffects. Similarly some display devices, such as projectors, includedouble-buffering in the electronics, effectively doubling the displaylatency. The desire for 3D televisions and reduced motion artifacts isdriving the development of faster LCDs, however, the physics of theliquid crystals themselves make performance of traditional LCD's beyond480 Hz unlikely. In an embodiment, the low latency system describedherein may use an LCD display. In contrast to the performance of an LCDdisplay, OLED or AMOLED displays are capable of response times wellbelow 1 ms. Accordingly, in an embodiment, the high performance touch(or gesture) system described herein may be implemented on displayshaving fast response times, including, without limitation displays basedon one or more of the following technologies: OLED, AMOLED, plasma,electrowetting, color-field-sequential LCD, optically compensatedbend-mode (OCB or Pi-Cell) LCD, electronic ink, etc.

Latency Perception Studies

Studies were undertaken to determine what latencies in a direct touchinterface users perceive as essentially instantaneous. A prototypedevice represented in a block diagram in FIG. 4 shows an illustrativeembodiment of a basic architecture of a prototype high-performance touchsystem 400. In an embodiment, the high-speed input device 420 is amulti-touch resistive touch sensor having an active area of 24 cm×16 cm,and electronics that allow for very high-speed operation. The delaythrough this sensor is slightly less than 1 ms. In an embodiment, touchdata may be transmitted serially over an optical link.

In the illustrative testing system, the display 460 is a DLP Discovery4100 kit based on Texas Instruments' Digital Light Processingtechnology. The illustrative testing system utilizes front-projectiononto the touch sensor thus eliminating parallax error that might disturba user's perception of finger and image alignment. The DLP projectoremployed uses a Digital Micromirror Device (DMD), a matrix of mirrorswhich effectively turns pixels on or off at very high speed. The highspeed of the mirrors may be used to change the percentage time on vs.off to create the appearance of continuous colored images. In anembodiment, where only simple binary images are used, these can beproduced at an even higher rate. In the illustrative testing system, theprojector development system displays 32,000 binary frames/second at1024×768 resolution with latency under 40 μs. In the illustrativetesting system to achieve this speed, the video data is streamed to theDMD at 25.6 Gbps.

In the illustrative testing system, to achieve minimal latency, alltouch processing is performed on a dedicated FPGA 440—no PC or operatingsystem is employed between the touch input and the display of lowlatency output. The DLP kit's onboard XC5VLX50 application FPGA may beused for processing the touch data and rendering the video output. A USBserial connection to the FPGA allows parameters to be changeddynamically. In the illustrative testing system, latency can be adjustedfrom 1 ms to several hundred ms with 1 ms resolution. Different testingmodes can be activated, and a port allows touch data to be collected foranalysis.

In the illustrative testing system, to receive touch data from thesensor 420, the system communicates through a custom high-speed UART. Tominimize latency, a baud rate of 2 Mbps can be used, which represents ahigh baud rate that can be used without losing signal integrity due tohigh frequency noise across the communication channel. In theillustrative testing system, the individual bytes of compressed touchdata are then processed by a touch detection finite state machineimplemented on the FPGA 440. The finite-state machine (FSM)simultaneously decodes the data and performs a center-of-massblob-detection algorithm to identify the coordinates of the touches. Inthe illustrative testing system, the system is pipelined such that eachiteration of the FSM operates on the last received byte such that nobuffering of the touch data occurs.

In the illustrative testing system, the touch coordinates are then sentto a 10-stage variable delay block. Each delay stage is a simple FSMwith a counter and takes a control signal that indicates the number ofclock cycles to delay the touch coordinate, allowing various levels oflatency. The delay block latches the touch sample at the start of theiteration and waits for the appropriate number of cycles before sendingthe sample and latching the next. The delay block therefore lowers thesample rate by a factor of the delay count. In an embodiment, to keepthe sample rate at a reasonable level, 10 delay stages can be used, sothat, for example, to achieve 100 ms of latency, the block waits 10 msbetween samples for a sample rate of 100 Hz. In the illustrative testingsystem, to run basic applications, a MicroBlaze soft processor is usedto render the display.

In an embodiment, the testing system may use a hard coded control FSM inplace of the MicroBlaze for improved performance. In an embodimentanother soft processor may be used. In the illustrative testing system,the MicroBlaze is a 32-bit Harvard architecture RISC processor optimizedto be synthesized in Xilinx FPGAs. The MicroBlaze soft processorinstantiation allows the selection of only the cores, peripherals, andmemory structures required. In the illustrative testing system, inaddition to the base MicroBlaze configuration, an interrupt controllercan be used, for example, GPIOs for the touch data, a GPIO to set thevariable latency, a BRAM memory controller for the image buffer, and aUART unit to communicate with a PC. In the illustrative testing system,the MicroBlaze is clocked at 100 MHz. The MicroBlaze uses an interruptsystem to detect valid touch coordinates. A touch ready interrupt eventis generated when valid touch data arrives on the GPIOs from the delayblock, and the corresponding image is written to the image buffer.Because of the non-uniform nature of an interrupt-based system, theexact latency cannot be computed, but, by design, it is insignificant incomparison to the 1 ms latency due to the input device.

In the illustrative testing system, the image buffer is synthesized inon-chip BRAM blocks. These blocks can provide a dual-port high-speedconfigurable memory buffer with enough bandwidth to support highframe-rate display. In the illustrative testing system, the image bufferis clocked at 200 MHz with a bus width of 128 bits for a total bandwidthof 25.6 Gbps, as needed by the DLP. Finally, the DMD controllercontinuously reads out frames from the image buffer and generates thesignals with appropriate timing to control the DMD.

In the illustrative testing system, user input is sent simultaneously toa traditional PC, and is processed to produce a traditional, higherlatency, response. This higher latency response is output by atraditional data projector, aligned to overlap with the projected lowerlatency response.

Studies were conducted to determine the precise level of performancethat users are able to perceive when performing common tasks on a touchscreen interface. To that end, studies were conducted to determine thejust-noticeable difference (JND) of various performance levels. JND isthe measure of the difference between two levels of a stimulus which canbe detected by an observer. In this case, the JND is defined as thethreshold level at which a participant is able to discriminate betweentwo unequal stimuli—one consistently presented at the same level, termedthe reference, and one whose value is changed dynamically throughout theexperiment, termed the probe. A commonly accepted value for the JND atsome arbitrary reference value is a probe at which a participant cancorrectly identify the reference 75% of the time. A probe value thatcannot be distinguished from the reference with this level of accuracyis considered to be “not noticeably different” from the reference.

Studies were conducted to determine the JND level of the probe latencywhen compared to a maximum performance of 1 ms of latency, which servedas the reference. While such a determination does not provide anabsolute value for the maximum perceptible performance, it can serve asour “best case” floor condition against which other levels of latencycan be measured, given that it was the fastest speed our prototype couldachieve. It was found participants are able to discern latency valuesthat are significantly lower (<20 ms) which typical current generationhardware (e.g., current tablet and touch computer) provides (˜50-200ms).

Ten right-handed participants (3 female) were recruited from the localcommunity. Ages ranged between 24 and 40 (mean 27.80, standard deviation4.73). All participants had prior experience with touch screen devices,and all participants owned one or more touch devices (such as an iOS- orAndroid-based phone or tablet). Participants were repeatedly presentedwith pairs of latency conditions: the reference value (1 ms) and theprobe (between 1 and 65 ms of latency). Participants dragged theirfinger from left to right, then right to left on the touch screendisplay. While any dragging task would have been suitable, left/rightmovements reduce occlusion in high-latency cases. Participants wereasked to move in both directions to ensure they did not “race through”the study. Beneath the user's contact point, the system rendered a solidwhite 2 cm×2 cm square as seen in FIG. 1. The speed of movement was leftto be decided by the participants. The order of the conditions wasrandomized for each pair. The study was designed as a two-alternativeforced-choice experiment; participants were instructed to choose, withineach trial, which case was the reference (1 ms) value and were notpermitted to make a “don't know” or “unsure” selection. After each pair,participants informed the experimenter which of the two was “faster”.

In order for each trial to converge at a desired JND level of 75%, theamount of added latency was controlled according to an adaptivestaircase algorithm. Each correct identification of the reference valuecaused a decrease in the amount of latency in the probe, while eachincorrect response caused the probe's latency to increase. In order toreach the 75% confidence level, increases and decreases followed thesimple weighted up-down method described by Kaernbach (Kaernbach, C.1991. Perception & Psychophysics 49, 227-229), wherein increases had athree-fold multiplier applied to the base step size, and decreases werethe base step size (initially 8 ms).

When a participant responded incorrectly after a correct response, orcorrectly after an incorrect response, this was termed a reversal as itcaused the direction of the staircase (increasing or decreasing) toreverse. The step size, initially 8 ms, was halved at each reversal, toa minimum step size of 1 ms. This continued until a total of 10reversals occurred, resulting in a convergence at 75% correctness. Eachparticipant completed eight staircase “runs.” Four of these started atthe minimum probe latency (1 ms) and four at the maximum (65 ms). Thehigher starting value of the staircase was chosen because it roughlycoincides with commercial offerings, and because pilot testing made itclear that this value would be differentiated from the 1 ms referencewith near 100% accuracy, avoiding ceiling effects. Staircases were runtwo at a time in interleaved pairs to prevent response biases that wouldotherwise be caused by the participants' ability to track their progressbetween successive stimuli. Staircase conditions for each of these pairswere selected at random without replacement from possibilities (2starting levels×4 repetitions). The entire experiment, including breaksbetween staircases, was completed by each participant within a single1-hour session.

The study was designed to find the just-noticeable difference (JND)level for latency values greater than 1 ms. This JND level is commonlyagreed to be the level where the participant is able to correctlyidentify the reference 75% of the time. Participant JND levels rangedfrom 2.38 ms to 11.36 ms, with a mean JND across all participants of6.04 ms (standard deviation 4.33 ms). JND levels did not varysignificantly across the 8 runs of the staircase for each participant.Results for each participant appear in FIG. 5.

The results show participants were able to discern differences inlatency far below the typical threshold of consumer devices (50-200 ms).It is noted that participants were likely often determining latency byestimating the distance between the onscreen object and their finger asit was moved around the touch screen; this is an artifact of inputprimitives used in UIs (specifically, dragging). Testing a differentinput primitive (tapping, for example) would exhibit differentperceptions of latency. Results confirm that an order-of magnitudeimprovement in latency would be noticed and appreciated by users oftouch devices.

An Architecture for a Low-Latency Direct Touch Input Device

In an embodiment, a software interface may be designed that enablesapplication developers to continue to use toolkit-based applicationdesign processes, but enable those toolkits to provide feedback atextremely low latencies, given the presence of a low-latency system. Inan embodiment, the systems and methods outlined in the presentdisclosure may be implemented on the model-view-controller (“MVC”) modelof UI development, upon which many UI toolkits are based. An MVC permitsapplication logic to be separated from the visual representation of theapplication. In an embodiment, an MVC may include, a second, overlaid defacto view for the application. In particular, in an embodiment, touchinput receives an immediate response from the UI controls, which isbased in part on the state of the application at the time the touch ismade. The goal is to provide nearly immediate responses that arecontextually linked to the underlying application.

Previous work on application independent visual responses to touch arecompletely separate from even the visual elements of the UI, addingvisual complexity. In an embodiment, according to the systems andmethods outlined herein, a set of visual responses are more fullyintegrated into the UI elements themselves so as to reduce visualcomplexity. Thus, in an embodiment, where the particular visuals shownprovide a de facto “mouse pointer” for touch, the goal is to integratehigh performance responses into the controls themselves, providing amore unified visualization. None the less, in an embodiment, the systemsand methods allow the rendering of context-free responses by thelow-latency subsystem, which are later merged with responses from thehigh-latency subsystem. In an embodiment, visuals need not be presentedin the same rendering pipeline as the rest of the system's response.Instead, a system or method which utilizes hybrid feedback as discussedherein may present lower latency responses to user input in addition tothe higher latency responses generated by the traditional system.

Thus, in an embodiment, accelerated input interactions are designed suchthat the traditional direct-touch software runs as it would normally,with a high-latency responses, while an additional set of feedback,customized for the UI element, is provided at a lower latency; with atarget of user-imperceptible latency. In an embodiment, these two layersare combined by superimposing two or more images. In an embodiment, twocombined images may include one projected image from the low-latencytouch device, and a second from a traditional projector connected to adesktop computer running custom touch software, receiving input from thelow-latency subsystem.

The two projector solution described above is meant only to serve as oneparticular embodiment of the more general idea of combining a lowlatency response and a traditional response. In an embodiment, thevisual output from the low and high-latency sub-systems are logicallycombined in the display buffer or elsewhere in the system before beingsent to the display, and thus, displayed. In an embodiment, transparent,overlapping displays present the low and high-latency output to theuser. In an embodiment, the pixels of a display are interlaced so thatsome are controlled by the low latency subsystem, and some arecontrolled by the high-latency sub-system; through interlacing, thesedisplays may appear to a user to overlap. In an embodiment, framespresented on a display are interlaced such that some frames arecontrolled by the low latency subsystem and some frames are controlledby the high-latency sub-system; through frame interlacing, the displaymay appear to a user to contain a combined image. In an embodiment, thelow-latency response may be generated predominantly or entirely inhardware. In an embodiment, the low-latency response may be generatedfrom input sensor data received directly from the input sensor. In anembodiment, the low-latency response is displayed by having a highbandwidth link to the display hardware.

In designing a user interface for a low-latency subsystem, one or moreof the following constraints may be considered:

-   -   Information: any information or processing needed from the        high-latency subsystem in order to form the system's response to        input will, necessarily, have high latency, unless such        information or processing is e.g., pre-rendered or pre-served.    -   Performance: the time allowed for formation of responses in low        latency is necessarily limited. Even with hardware acceleration,        the design of responses must be carefully performance-driven to        guarantee responses meet the desired low latency.    -   Fidelity: the fidelity of the rendered low-latency image may be        indistinguishable from the higher-latency rendering (indeed, it        may be pre-rendered by the high latency system); additional        constraints may be placed on fidelity to improve performance,        such as, e.g., that visuals are only monochromatic, and/or        limited to visual primitives, and/or that the duration or        characteristics of audio or haptic responses are limited.        Constraints of this type may be introduced by various elements        of the system, including acceleration hardware or by the output        hardware (such as the display, haptic output device, or        speakers).    -   Non-Interference: in embodiments where responses are hybridized        combinations, some of the application's response may be        generated in the low-latency layer, and some in the high-latency        layer, a consideration may be how the two are blended, e.g., to        provide a seamless response to the user's input. In an        embodiment, low-latency responses do not interfere with any        possible application response, which will necessarily occur        later. In an embodiment, interference may occur between a        low-latency response and the traditional response, but the        interference may be handled through design, or through blending        of the responses.

In an embodiment, a design process was conducted to create a set ofvisual UI controls with differentiated low and high latency visualresponses to touch. A metaphor was sought which would enable a seamlesstransition between the two layers of response. These visualizationsincluded such information as object position and state. The designs wereculled based on feasibility using the above-described constraints. Thefinal design of such embodiment was based on a heads-up display (HUD)metaphor, similar to the visualizations used in military aircraft. TheHUD was suitable, since traditional HUDs are geometrically simple, andit is relatively easy to implement a geometrically simple display at anauthentic fidelity. The HUD represents just one example of two visuallayers being combined, though in many HUDs, a computerized display issuperimposed on video or the “real world” itself. Accordingly, a HUD isgenerally designed to be non-interfering.

Based on the HUD metaphor, an exemplary set of touch event and UIelement-specific low-latency layer visualizations were developed for aset of UI elements found in many direct-touch systems. These exemplaryelements are both common and representative; their interactions (taps,drags, two-finger pinching) cover the majority of the interaction spaceused in current direct-touch devices. The low-latency responsesdeveloped in such an embodiment are described in Table 1, and they areshown in FIG. 6-8.

TABLE 1 Accelerated visuals for each element and touch event, whichcompliment standard high latency responses to touch input. Element TouchDown Touch Move Touch Up Button Bounds outlined (none) If within bounds,2^(nd) (FIG. 6) 610 outline 620, else none Draggable/Resizable Boundsoutlined Outline changes and moves with input Outline 710 fades when(FIG. 7) 710 position 720 and/or scales with input high-latency layercatches gesture 730 up Scrollable List List item outlined If scrollgesture, list edges highlight If list item selection, (FIG. 8) 810 830to scroll distance. outline 820 scales down If during scroll gesture,edge and fades highlights 840) fade as high-latency layer catches up

These three elements represent broad coverage of standard UI toolkitsfor touch input. Most higher-order UI elements are composed of thesesimpler elements (e.g. radio buttons and checkboxes are both “buttons,”a scrollbar is a “draggable/resizable” with constrained translation androtation). The accelerated input system and method described hereindepends on the marriage of visuals operating at two notably differentlatency levels; this latency difference has been incorporated into thedesign of low-latency visualizations. In an embodiment, users may beinformed of the state of both systems, with a coherent synchronizationas the visual layers come into alignment. In an embodiment, a user maybe able to distinguish between the high and low latency portions ofsystem feedback. In an embodiment, the visual elements are blended in amanner that provides no apparent distinction between the low-latencyresponse and the traditional response.

In an embodiment, an application developer utilizes a toolkit to buildtheir application through the normal process of assembling GUI controls.Upon execution, the UI elements bifurcate their visualizations, withhigh- and low-latency visualizations rendered and overlaid on a singledisplay. An embodiment of information flow through such a system is asshown in FIG. 9. Information flows into the system from an input device910 and is initially processed by an input processing unit (IPU) 920,programmed via an IPU software toolkit 930. UI events are then processedin parallel by two subsystems, a low-latency, low fidelity subsystem940, and a high-latency subsystem 950 such as, for example, conventionalsoftware running in a conventional software stack. In an embodiment, thelow-latency, low fidelity subsystem 940 may be implemented in hardware,such as the FPGA 440 of FIG. 4.

The bifurcation described in this embodiment creates a fundamentalcommunication problem where any parameterization of the initialresponses provided by the low-latency subsystem 940 required byapplication logic must be defined before the user begins to give input.Any response which requires processing at the time of presentation bythe application will introduce a dependency of the low-latency system940 upon the high-latency system 950, and may therefore introduce lagback into the system. In an embodiment, later stages of the low-latencysystem's 940 response to input may depend on the high latency subsystem950. In an embodiment, dependency of the later stages of a low-latencysubsystem's 940 response to input on the high latency subsystem 950 ismanaged such that the dependency does not introduce additional latency.In an embodiment the dependency would be avoided entirely.

In an embodiment, UI element logic may be built into the low-latencysubsystem. Between user inputs, the application executing in thehigh-latency subsystem 950, has the opportunity to provide parametersfor the low-latency subsystem's 940 model of the UI elements. Thus, inan embodiment, the MVC model of UI software design may be extended byproviding a separate controller responsible for low-latency feedback. Inan embodiment, in the software design, one or more of the following canbe specified for each control:

-   -   Element type (e.g., button, draggable object, scrollable list,        etc.).    -   Bounding dimensions (e.g., x position, y position, width,        height, etc.).    -   Conditional: additional primitive information (e.g., size of        list items in the case of a scrollable list, etc.).

In an embodiment, logic for a given element-type's response to touchinput is stored in the low-latency subsystem 940. Furtherparameterization of the low-latency sub-system's responses to user inputcould be communicated in the same manner, allowing a greater degree ofcustomization. In an embodiment, sensor data is processed to generateevents (or other processed forms of the input stream), which are thenseparately distributed to the low-latency subsystem 940 and to thehigh-latency subsystem 950. Events may be generated at different ratesfor the low-latency subsystem 940 and high-latency subsystem 950,because the low-latency subsystem is capable of processing events fasterthan the high-latency subsystem, and sending events to the high-latencysub-system at a high rate may overwhelm that subsystem. The low- andhigh-latency subsystems' response to user input is therefore independentbut coordinated. In an embodiment, one subsystem acts as the “master,”setting state of the other subsystem between user inputs. In anembodiment, the relationship between the low- and high-latencysubsystems includes synchronization between the two subsystems. In anembodiment, the relationship between the low- and high-latencysubsystems includes the ability of the high-latency subsystem to offloadprocessing to the low-latency subsystem 940. In an embodiment, therelationship between the low- and high-latency subsystems includes theability of the low-latency subsystem 940 to reduce its processing Loadand/or utilize the high-latency subsystem 950 for pre-processing orpre-rendering. In an embodiment, a second graphical processing andoutput system's response is dependent upon a first graphical processingand output system, and state information is passed from the firstgraphical processing and output system to the second graphicalprocessing and output system. In such embodiments, information passedfrom the first graphical processing and output system to the secondgraphical processing and output system is comprised of one or morepieces of data describing one or more of the graphical elements in theuser interface. This data may be, e.g., the size, the location, theappearance, alternative appearances, response to user input, and thetype of graphical elements in the user interface. The data passed fromthe first graphical processing and output system to the second graphicalprocessing and output system may be stored in high-speed memoryavailable to the second graphical processing and output system. Thepassed data may describe the appearance and/or behavior of a button, aslider, a draggable and/or resizable GUI element, a scrollable list, aspinner, a drop-down list, a menu, a toolbar, a combo box, a movableicon, a fixed icon, a tree view, a grid view, a scroll bar, a scrollablewindow, or a user interface element.

In an embodiment, an input processing system performs decimation on theuser input signals before they are received by one or both of the firstor second graphical processing and output systems. The decimated inputsignals or non-decimated signals are chosen from the set of all inputsignals based on information about the user interface sent from thefirst graphical processing and output system. The decimation of inputsignals may be performed by logically combining the set of input signalsinto a smaller set of input signals. Logical combination of inputsignals may be performed through windowed averaging. The decimationconsiders the time of the user input signals when reducing the size ofthe set of input signals. The logical combination of input signals canbe performed through weighted averaging. In an embodiment, the userinput signals received by the first and second graphical processing andoutput systems have been differentially processed.

In an embodiment, communication between the high-latency and low-latencylayers may be important. Some points which are considered in determininghow the high- and low-latency subsystems remain synchronized aredescribed below:

-   -   Latency differences: Low-latency responses may use information        about the latency difference between the high- and low-latency        layers in order to synchronize responses. In an embodiment,        these latency values are static, and thus preprogrammed into the        FPGA. In an embodiment where latency levels may vary in either        subsystem, it may be advantageous to fix the latency level at an        always-achievable constant rather than having a dynamic value        that may become unsynchronized, or provide an explicit        synchronization mechanism. In an embodiment where latency levels        may vary in either subsystem, a dynamic value may be used,        however, care should be taken to avoid becoming unsynchronized.        In an embodiment where latency levels may vary in either        subsystem, an explicit synchronization mechanism may be provided        between the subsystems 940, 950.    -   Hit testing: Hit testing decisions are often conditional on data        regarding the visual hierarchy and properties of visible UI        elements. In an embodiment, this consideration can be resolved        by disallowing overlapping bounding rectangles, requiring a        flat, ‘hit test friendly’ map of the UI. In an embodiment        separate hit testing may provide the necessary information        (object state, z-order, and listeners) to the low-latency        subsystem. In an embodiment both the low- and high-latency        subsystems may conduct hit testing in parallel. In an embodiment        the low-latency subsystem conducts hit testing, and provides the        results to the high-latency subsystem.    -   Conditional responses: Many interface visualizations are        conditional not only on immediate user input, but on further        decision-making logic defined in the application logic.

Two illustrative examples of conditional response logic are as follows:Consider a credit-card purchase submission button, which is programmedto be disabled (to prevent double billing) when pressed, but only uponvalidation of the data entered into the form. In such a case, thebehavior of the button is dependent not only on an immediate userinteraction, but is further conditional on additional information andprocessing. Consider also linked visualizations, such as the one shownin FIG. 10. In this case, feedback is provided to the user not only bythe UI element they are manipulating 1010, but also by a second UIelement 1020. These examples could be programmed directly into alow-latency subsystem.

In an embodiment, the division between the high- and low-latencysubsystems may be independent of any user interface elements. Indeed,the division of responsibility between the subsystems can be customizedbased on any number of factors, and would still be possible in systemsthat lack a user interface toolkit, or indeed in a system which includedmechanisms to develop applications both within and without the use of aUI toolkit which might be available. In an embodiment, the division ofresponsibility between the two subsystems can be dynamically alteredwhile the subsystems are running. In an embodiment, the UI toolkititself may be included within the low-latency subsystem. The ability tocustomize responses can be provided to application developers in anumber of ways without departing from the systems and methods hereindescribed. In an embodiment, responses may be customized as parametersto be adjusted in UI controls. In an embodiment, responses may becustomized by allowing for the ability to provide instructions directlyto the low-latency subsystem, in code which itself executes in thelow-latency subsystem, or in another high- or low-latency component. Inan embodiment, the state of the low-latency subsystem could be set usingdata generated by application code, e.g., at runtime.

While many of the examples described above are provided in the contextof a touch input, other embodiments are contemplated, including, withoutlimitation, pen input, mouse input, indirect touch input (e.g., atrackpad), in-air gesture input, oral input and/or other inputmodalities. The architecture described would be equally applicable toany sort of user input event, including, without limitation, mixed inputevents (i.e., supporting input from more than one modality). In anembodiment, mixed input devices may result in the same number of eventsbeing generated for processing by each of the low- and high-latencysubsystems. In an embodiment, mixed input devices would bedifferentiated in the number of events generated, thus, for example,touch input might have fewer events than pen input. In an embodiment,each input modality comprises its own low-latency subsystem. In anembodiment, in systems comprising multiple low-latency subsystems formultiple input modalities, the subsystems might communicate tocoordinate their responses. In an embodiment, in systems comprisingmultiple low-latency subsystems for multiple input modalities, themultiple subsystems may share a common memory area to enablecoordination.

Input Processing

In an embodiment of the invention, low-latency input data from the inputhardware is minimally processed into a rapid stream of input events.This stream of events is sent directly to the low-latency sub-system forfurther processing. Events from this same stream may then be deleted, orthe stream may be otherwise reduced or filtered, before being sent tothe high-latency subsystem. Events may be generated at different ratesfor the low-latency subsystem 940 and high-latency subsystem 950 becausethe low-latency subsystem is capable of processing events faster thanthe high-latency subsystem, and sending events to the high-latencysub-system at a high rate may overwhelm that subsystem. The low- andhigh-latency subsystems' response to user input may therefore beindependent but coordinated.

The reduction of events can be optimized. In an embodiment,representative events may be selected among candidate events based oncriteria associated with one or more of the application, the UI element,the input device, etc. An example of this for pen input when the user isdrawing digital ink strokes might include selecting events which fitbest to the user's drawn stroke. Another example for speech input is tofavor events where subsequent events in the output stream would havesimilar volume, thereby “evening out” the sound coming from themicrophone. Another example for touch input is to favor events whichwould result in the output event stream having a consistent speed,providing more “smooth” output. This form of intelligent reduction actsas an intelligent filter, without reducing performance of thehigh-latency subsystem. In an embodiment, new events (e.g., consolidatedevents or pseudo-events) could be generated which represent an aggregateof other events in the input stream. In an embodiment, new events (e.g.,corrected events, consolidated events or pseudo-events) may be generatedthat represent a more desirable input stream, e.g., a correction orsmoothing. For example, for in-air gesture input, for every 10 eventsfrom the high-speed input device, the high-latency subsystem may be sentthe same number or fewer events which provide an “average” of actualinput events, thus smoothing the input and removing jitter. New eventscould also be generated which are an amalgam of multiple “desired”levels of various parameters of an input device. For example, if theintelligent reductions of the tilt and pressure properties of a styluswould result in the selection of different events, a single, new, eventobject could be created (or one or more existing event objects modified)to include the desired values for each of these properties.

In an embodiment, an IPU or low-latency subsystem system might be usedto provide the high-latency system with processed input information. Oneor more of methods could be used to coordinate the activities of the twosubsystems. These include:

-   -   a. In an embodiment, the low-latency subsystem can respond to        all user input immediately, but wait for the user to stop the        input (e.g. lifting a finger or pen, terminating a gesture)        before providing the input to the high-latency system. This has        an advantage of avoiding clogging the system during user        interaction while still processing the totality of the data.    -   b. In an embodiment, the low-latency system can provide a        reduced estimate of input in near real-time; and may optionally        store a complete input queue that can be available to the        high-latency system upon request.    -   c. In an embodiment, user feedback may be divided into two        steps. The first, a low-latency feedback, would provide a rough,        immediate representation of user input 1130 in FIG. 11. The        second, a high-latency system response 1140, could replace the        first 1130, whenever the high-latency system is able to compute        a refined response, for example after lift-off of the pen 1150        tip. Alternatively, the high latency feedback could be        continuously “catching up” to (and possibly subsuming) the low        latency feedback.    -   d. In an embodiment, the low-latency system can infer simple        gesture actions from the input stream, and thus generate gesture        events which are included in the input queue in addition to, or        replacing, the raw events.    -   e. In an embodiment, an IPU or low-latency subsystem can use        multiple input positions to predict future input positions. This        prediction can be passed along to the high-latency subsystem to        reduce its effective latency.    -   f. In an embodiment, algorithms which may benefit from        additional samples, or earlier detection, are executed in the        IPU or low-latency subsystem. In an embodiment, the execution of        these events can be limited in time. For example, the initial 50        events can be used to classify an input as a particular finger,        or to differentiate between finger and pen inputs. In an        embodiment, these algorithms can run continuously.    -   g. In an embodiment, the process of the low-latency subsystem        passing a stream of events to the high-latency subsystem might        be delayed in order to receive and process additional sequential        or simultaneous related inputs which might otherwise be        incorrectly regarded as unrelated inputs. For example, the        letter “t” is often drawn as two separate, but related, strokes.        In the normal course, the portion of the input stream passed        from the low-latency to the high-latency system would include a        “pen up” signal at the end of drawing the first line. In an        embodiment, the reduction process waits for the very last frame        of input within the sample window to pass along an “up” event,        in case the pen is again detected on the display within the        window, thus obviating the need for the event.

Hardware Architecture

In an embodiment, data flows through two overlapping paths through thecomponents of the system to support both high- and low-latency feedback.FIG. 12 shows one such system, which includes an Input Device 1210, anIPU 1220, a System Bus 1230, a CPU 1240 and a GPU 1280 connected to aDisplay 1290. A User 1200 performs input using the Input Device 1210.This input is sensed by the IPU 1220 which in various embodiments can beeither an FPGA, ASIC, or additional software and hardware logicintegrated into a GPU 1280, MPU or SoC. At this point, the control flowbifurcates and follows two separate paths through the system. Forlow-latency responses to input, the IPU 1220 sends input events throughthe System Bus 1230 to the GPU 1280, bypassing the CPU 1240. The GPU1280 then rapidly displays feedback to the User 1200. For high-latencyresponse to input, the IPU 1220 sends input events through the SystemBus 1230 to the CPU 1240, which is running the graphical application andwhich may interact with other system components. The CPU 1240 then sendscommands via the System Bus 1230 to the GPU 1280 in order to providegraphical feedback to the User 1200. The low-latency path from InputDevice 1210 to IPU 1220 to System Bus 1230 to GPU 1280 is primarilyhardware, and operates with low-latency. The high-latency path fromInput Device 1210 to IPU 1220 to System Bus 1230 to CPU 1240 back toSystem Bus 1230 to GPU 1280 is high-latency due to the factors describedearlier in this description. In a related embodiment, the Input Device1210 communicates directly with the GPU 1280 and bypasses the System Bus1230.

FIG. 13 shows a familiar programming paradigm called Model ViewController. In this paradigm, the User 1300 performs input on theController 1310, which in turn manipulates the Model 1320 based on thisinput. Changes in the Model 1320 result in changes to the View 1330,which is observed by the User 1300. Some of the latency addressed by thepresent invention is due to latency in the input, communication amongthese components, and display of the graphics generated by the View 1330component.

FIG. 14 shows an embodiment of an architecture that supports developingand running applications on a system with blended high- and low-latencyresponses to user input. The User 1400 performs input with the inputdevice 1410. This input is received by the IPU 1420. The IPU 1420 sendsinput events simultaneously to the Controller 1430 running in thehigh-latency subsystem via traditional mechanisms and to theViewModel(L) 1490 running in the low-latency subsystem. Input is handledby the Controller 1430, which manipulates the Model 1440 running in thehigh-latency subsystem, which may interact with data in volatile memory1450, fixed storage 1470, network resources 1460, etc. (all interactionsthat introduce lag). Input events received by the ViewModel(L) 1490result in changes to the ViewModel(L) which are reflected in changes tothe View(L) 1491, which is seen by the User 1400. Changes to the Model1440 result in changes to the high-latency subsystem's View(H) 1480,which is also seen by the User 1400. In an embodiment, these two typesof changes seen by the user are shown on the same display. In anembodiment, these two types of changes are reflected to the user viaother output modalities (such as, e.g., sound or vibration). In anembodiment, between inputs, the Model 1440 updates the state of theViewModel(L) 1490 and View(L) 1491 so that the ViewModel(L) 1490contains the needed data to present the GUI's components in the correctlocation on the system's display and so that the ViewModel(L) 1490 cancorrectly interpret input from the IPU 1420 in the context of thecurrent state of the Model 1440; and so that the View(L) 1491 cancorrectly generate graphics for display in the context of the currentstate of the Model 1440.

By way of example, consider a touch-sensitive application with a buttonthat among its functions responds to a user's touch by changing itsappearance indicating that it has been activated. When the applicationis run, the application reads the location, size, and details of theappearance of the button from memory and compiled application code. TheView(H) 1480 code generates the necessary graphics which are presentedto the user to display this button. The Model 1440 updates the state ofthe ViewModel(L) 1490 to record that this graphical element is a button,and that it should change appearances from a “normal” appearance to a“pressed” appearance when touched. The Model 1440 also updates the stateof the View(L) 1491 to record the correct appearance for the “normal”and “pressed” states in the ViewModel(L) 1490. This appearance may be adescription of low-fidelity graphical elements, or a complete raster todisplay. In this example, the “pressed” state is represented by adisplaying a white box around the button's position.

A User touches the touch-screen display, and input data describing thattouch is received less than 1 ms later by the IPU 1420. The IPU 1420creates an input event representing a touch-down event from the inputdata and sends this input event to the application Controller 1430. TheController 1430 manipulates the Model 1440. In this case, the Controller1430 is indicating to the Model 1440 that the button has been touchedand that the application should perform whatever commands are associatedwith this button. At the same time that the IPU 1420 sends an event tothe Controller 1430, it sends an event to the ViewModel(L) 1490indicating that the button has been touched. The ViewModel(L) 1490 waspreviously instructed by the Model 1440 as to what to do in the case ofa touch, and in this case it responds to the touch event by changing itsstate to “pressed”. The View(L) 1491 responds to this change bydisplaying a white box around the button, feedback that corresponds toits “pressed” appearance. The change to the Model 1440 that the buttonis touched causes an update of View(H) 1480, so that it too reflectsthat button is now touched. The User, who see the output of both View(H)1480 and View(L) 1491, sees the immediate feedback of their touch byView(L) 1491 followed a fraction of a second later by the feedback fromView(H) 1480.

Throughout the text of this application, the word “event” is used todescribe information describing attributes of user input. This term isused generally, and thus includes embodiments in which event drivenarchitectures are employed (with actual event objects being passedbetween software elements), as well as more basic input streams in whichthe “event” being described is simply present in the stream ofinformation. Such events may be, e.g., non-object-orient types of eventsor object-oriented types events.

The present system and methods are described above with reference toblock diagrams and operational illustrations of methods and devicescomprising a computer system capable of receiving and responding to userinput. It is understood that each block of the block diagrams oroperational illustrations, and combinations of blocks in the blockdiagrams or operational illustrations, may be implemented by means ofanalog or digital hardware and computer program instructions. Thesecomputer program instructions may be provided to a processor of ageneral purpose computer, special purpose computer, ASIC, or otherprogrammable data processing apparatus, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, implements the functions/acts specified inthe block diagrams or operational block or blocks. In some alternateimplementations, the functions/acts noted in the blocks may occur out ofthe order noted in the operational illustrations. For example, twoblocks shown in succession may in fact be executed substantiallyconcurrently or the blocks may sometimes be executed in the reverseorder, depending upon the functionality/acts involved.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

What is claimed is:
 1. A system for processing user input, comprising:display comprising a visualization of a user interface; user inputdevice comprising at least one selected from the group consisting oftouch input and pen input, the user input device adapted to outputsignals corresponding to user input; input processing system operativelyconnected to the user input device, the input processing system adaptedto receive the signals corresponding to user input and to emit signalscorresponding to the received signals; first graphical processing andoutput system comprising software running in a software stack, the firstgraphical processing and output system adapted to receive at least someof the emitted signals and to generate high-latency data that can affectthe visualization of the user interface on the display and to output thehigh-latency data for use by the display in response to the at leastsome of the emitted signals; second graphical processing and outputsystem implemented at least partially in hardware, the second graphicalprocessing and output system adapted to substantially simultaneouslyreceive the at least some of the emitted signals and to generatelow-latency data that can affect the visualization of the user interfaceon the display and to output the generated low-latency data for use bythe display in response to the at least some of the emitted signals;wherein, with respect to the response to the at least some of theemitted signals, the second graphical processing and output system isadapted to output the generated low-latency data with low latencyrelative to the output of the high-latency data by the first graphicalprocessing and output system; and the display being configured todisplay at least some of the low-latency data and at least some of thehigh-latency data on the visualization of the user interface.
 2. Thesystem for processing user input according to claim 1, wherein thelow-latency data is generated by associating data corresponding to adefined response with one or more of the at least some of the emittedsignals.
 3. The system for processing user input according to claim 1,wherein the high-latency data is generated by rendering a response toone or more of the at least some of the emitted signals.
 4. The systemfor processing user input according to claim 1, wherein the high-latencydata and the low-latency data have substantially equal fidelity.
 5. Thesystem for processing user input according to claim 1, wherein thehigh-latency data and the low-latency data have unequal fidelity.
 6. Thesystem for processing user input according to claim 5, wherein at leastsome of the high-latency data is of higher fidelity than thecorresponding low-latency data.
 7. The system for processing user inputaccording to claim 1, wherein the second graphical processing and outputsystem is implemented, at least in part, in at least one selected fromthe group of field-programmable gate array (FPGA), application-specificintegrated circuit (ASIC), a microcontroller, a graphics processing unit(GPU), or a system on a chip (SoC).
 8. The system for processing userinput according to claim 1, wherein the second graphical processing andoutput system is implemented in logic integrated into an existingcomponent of a computing system.
 9. The system for processing user inputaccording to claim 8, wherein the existing component of the computingsystem comprises at least one selected from the group of a graphicsprocessing unit (GPU), input device controller, central processing unit(CPU), microcontroller, or system on a chip (SoC).
 10. The system forprocessing user input according to claim 1, wherein the first graphicalprocessing and output system includes state information reflecting atleast one state of the first graphical processing and output system, andthe second graphical processing and output system's response isdependent upon the state information.
 11. The system for processing userinput according to claim 1, wherein the second graphical processing andoutput system comprises user interface element logic.
 12. The system forprocessing user input according to claim 11, further comprising: UIelements data containing data regarding the visual hierarchy andproperties of visible UI elements; and wherein the second graphicalprocessing and output system is adapted to perform hit testing based oninformation in the UI elements data.
 13. The system for processing userinput according to claim 1, wherein the emitted signals are sent in astream to the first and second graphical processing and output system,and the second graphical processing and output system is adapted todelete one or more of the emitted signals from the stream, preventingsuch deleted signals from being part of the at least some of the emittedsignals corresponding to the received data that are received by thefirst graphical processing and output system.
 14. The system forprocessing user input according to claim 1, wherein the at least some ofthe emitted signals corresponding to the high-latency data for use bythe display differ from the at least some of the emitted signalscorresponding to the low-latency data.
 15. The system for processinguser input according to claim 1, wherein the second graphical processingand output system outputs the generated low-latency data for use by thedisplay within 10 ms of receiving a corresponding emitted signal. 16.The system for processing user input according to claim 1, wherein thesecond graphical processing and output system outputs the generatedlow-latency data for use by the display within 1 ms of receiving acorresponding emitted signal.
 17. The system for processing user inputaccording to claim 1, wherein a difference between at least some of thelow-latency data that can affect the visualization of the user interfaceand corresponding high-latency data that can affect the visualization ofthe user interface is perceptible to a user.
 18. The system forprocessing user input according to claim 1, wherein at least some of thelow-latency data that can affect the visualization of the user interfaceand at least some of the corresponding high-latency data that can affectthe visualization of the user interface is blended in a manner that isnot noticeable by a user.
 19. The system for processing user inputaccording to claim 1, configured to provide a low-latency systemresponse in a form that is dictated by application logic.
 20. The systemfor processing user input according to claim 1, wherein the form oflow-latency system response comprises a response or set of responsesselected from the group consisting of: an auditory response, a visualresponse, and a haptic response.
 21. The system for processing userinput according to claim 1, configured to provide a low-latency systemresponse in a form that is dictated by system logic.
 22. The system forprocessing user input according to claim 1, wherein the user inputdevice comprises a direct-touch input device employing at least one ofthe technologies selected from the group consisting of: resistive,direct illumination, frustrated total-internal reflection, diffuseillumination, projected capacitive, capacitive coupling, acoustic wave,and sensor-in-pixel.
 23. The system for processing user input accordingto claim 1, wherein the second graphical processing and output system'sresponse is independent of the first graphical processing and outputsystem.
 24. The system for processing user input according to claim 1,wherein high- and low-latency visualizations are combined on a singledisplay by at least one of: overlapping two projected images, logicallycombining the visualizations in a display buffer, overlapping twotransparent layers each capable of displaying one of the high- andlow-latency visualizations, interlacing pixels of the display such thatsome are filled from the low-latency visualizations and some are filledfrom the high-latency visualizations, or interlacing the frames of thedisplay such that some are filled from the low-latency visualizationsand some are filled from the high-latency visualizations.
 25. The systemfor processing user input according to claim 1, wherein the secondgraphical processing and output system is configured to process theevents with low fidelity with respect to a fidelity of the firstgraphical processing and output system.
 26. A system for processing userinput, comprising: display comprising a visualization of a userinterface; user input device adapted to output signals corresponding touser input; input processing system operatively connected to the userinput device, the input processing system adapted to receive the signalscorresponding to user input and to emit a stream of signalscorresponding to at least some of the received signals; first graphicalprocessing and output system adapted to receive at least a portion ofthe stream of signals and to generate high-latency data that can affectthe visualization of the user interface on the display and to output thehigh-latency data for use by the display in response to at least some ofthe signals in the at least a portion of the stream of signals receivedby the first graphical processing and output system; second graphicalprocessing and output system adapted to receive at least a portion ofthe stream of signals and to generate low-latency data that can affectthe visualization of the user interface on the display and to output thegenerated low-latency data for use by the display in response to the atleast some of the signals in the at least a portion of the stream ofsignals received by the second graphical processing and output system,the second graphical processing and output system being configured tooutput the generated low-latency data with low latency relative to theoutput of the high-latency data by the first output graphical processingand output system; and the display being configured to merge at leastsome of the low-latency data and at least some of the high-latency dataonto the visualization of the user interface.
 27. The system forprocessing user input claimed in claim 26, wherein the high-latency datais generated by rendering.
 28. The system for processing user inputaccording to claim 26, wherein the high-latency data and the low-latencydata have substantially equal fidelity.
 29. The system for processinguser input according to claim 26, wherein the high-latency data and thelow-latency data have unequal fidelity.
 30. The system for processinguser input according to claim 29, wherein at least some of thehigh-latency data is of higher fidelity than the correspondinglow-latency data.
 31. The system for processing user input according toclaim 26, wherein the second graphical processing and output system isimplemented, at least in part, in at least one selected from the groupof field-programmable gate array (FPGA), application-specific integratedcircuit (ASIC), a microcontroller, a graphics processing unit (GPU), ora system on a chip (SoC).
 31. The system for processing user inputaccording to claim 26, wherein the second graphical processing andoutput system is implemented in logic integrated into an existingcomponent of a computing system.
 33. The system for processing userinput according to claim 31, wherein the existing component of thecomputing system comprises at least one selected from the group of agraphics processing unit (GPU), input device controller, centralprocessing unit (CPU), microcontroller, or system on a chip (SoC). 34.The system for processing user input according to claim 26, wherein thefirst graphical processing and output system includes state informationreflecting at least one state of the first graphical processing andoutput system, and the second graphical processing and output system'sresponse is dependent upon the state information.
 35. The system forprocessing user input according to claim 26, wherein the secondgraphical processing and output system comprises user interface elementlogic.
 36. The system for processing user input according to claim 35,further comprising: UI elements data containing data regarding thevisual hierarchy and properties of visible UI elements; and wherein thesecond graphical processing and output system is adapted to perform hittesting based on information in the UI elements data.
 37. The system forprocessing user input according to claim 26, wherein the secondgraphical processing and output system is adapted to delete one or moreof the signals from the stream, preventing such deleted signals frombeing part of the at least a portion of the stream of signalscorresponding to at least some of the received data that are received bythe first graphical processing and output system.
 38. The system forprocessing user input according to claim 26, wherein the at least aportion of the stream of signals corresponding to the high-latency datadiffer from the at least a portion of signals corresponding to thelow-latency data.
 39. The system for processing user input according toclaim 26, wherein a difference between at least some of the low-latencydata that can affect the visualization of the user interface andcorresponding high-latency data that can affect the visualization of theuser interface is perceptible to a user.
 40. The system for processinguser input according to claim 26, wherein at least some of thelow-latency data that can affect the visualization of the user interfaceand at least some of the corresponding high-latency data that can affectthe visualization of the user interface is blended in a manner that isnot noticeable by a user.
 41. The system for processing user inputaccording to claim 26, configured to provide a low-latency systemresponse in a form that is dictated by application logic.
 42. The systemfor processing user input according to claim 41, wherein the form oflow-latency system response comprises a response or set of responsesselected from the group consisting of: an auditory response, a visualresponse, and a haptic response.
 43. The system for processing userinput according to claim 26, configured to provide a low-latency systemresponse in a form that is dictated by system logic.
 44. The system forprocessing user input according to claim 26, wherein the user inputdevice comprises a direct-touch input device employing at least one ofthe technologies selected from the group consisting of: resistive,direct illumination, frustrated total-internal reflection, diffuseillumination, projected capacitive, capacitive coupling, acoustic wave,and sensor-in-pixel.
 45. A system for processing user input, comprising:input device; input processing unit; high-latency subsystem; low-latencysubsystem implemented at least partially in hardware; input processingunit software for generating signals in response to user inputs; and,output device; wherein the low-latency subsystem receives the signalsand generates at least one low-latency output with low latency relativeto the high-latency subsystem and the high-latency subsystem processesat least some of the signals and generates at least one high-latencyoutput with high latency relative to the low-latency subsystem; whereinthe input device, the input processing unit, the high-latency subsystem,the low-latency subsystem, the input processing unit software and theoutput device being arranged such that: the low-latency processingsubsystem operates independently of and parallel to the high-latencyprocessing subsystem; and at least some of the user input signals areprocessed by both the low-latency subsystem and the high-latencysubsystem, the low-latency subsystem outputting to the output device aresponse to a given user input signal with low-latency and thehigh-latency subsystem outputting to the output device a response to thegiven user input signal with high-latency.
 46. The system for processinguser input claimed in claim 45, wherein high-latency data generated bythe high-latency subsystem is generated by rendering.
 47. The system forprocessing user input according to claim 45, wherein high-latency datagenerated by the high-latency subsystem and low-latency data generatedby the low-latency subsystem have substantially equal fidelity.
 48. Thesystem for processing user input according to claim 45, whereinhigh-latency data generated by the high-latency subsystem andlow-latency data generated by the low-latency subsystem have unequalfidelity.
 49. The system for processing user input according to claim45, wherein the high-latency subsystem generates high-latency data andthe low-latency subsystem generates low-latency data, and wherein atleast some of the high-latency data is of higher fidelity than thecorresponding low-latency data.
 50. The system for processing user inputaccording to claim 45, wherein the low-latency subsystem is implemented,at least in part, in at least one selected from the group offield-programmable gate array (FPGA), application-specific integratedcircuit (ASIC), a microcontroller, a graphics processing unit (GPU), ora system on a chip (SoC).
 51. The system for processing user inputaccording to claim 45, wherein the low-latency subsystem is implementedin logic integrated into an existing component of a computing system.52. The system for processing user input according to claim 51, whereinthe existing component of the computing system comprises at least oneselected from the group of a graphics processing unit (GPU), inputdevice controller, central processing unit (CPU), microcontroller, orsystem on a chip (SoC).
 53. The system for processing user inputaccording to claim 45, wherein high-latency subsystem includes stateinformation reflecting at least one state of the high-latency subsystem,and the low-latency subsystem's response is dependent upon the stateinformation.
 54. The system for processing user input according to claim45, wherein the low-latency subsystem comprises user interface elementlogic.
 55. The system for processing user input according to claim 54,further comprising: UI elements data containing data regarding thevisual hierarchy and properties of visible UI elements; and wherein thelow-latency subsystem is adapted to perform hit testing based oninformation in the UI elements data.
 56. The system for processing userinput according to claim 45, wherein the low-latency subsystem isadapted to delete one or more of the signals from the stream, preventingsuch deleted signals from being part of the at least a portion of thestream of signals corresponding to at least some of the received datathat are received by the high-latency subsystem.
 57. The system forprocessing user input according to claim 45, wherein the at least aportion of the stream of signals corresponding to the high-latency datadiffer from the at least a portion of signals corresponding to thelow-latency data.
 58. The system for processing user input according toclaim 45, wherein a difference between at least some of the low-latencydata that can affect the visualization of the user interface andcorresponding high-latency data that can affect the visualization of theuser interface is perceptible to a user.
 59. The system for processinguser input according to claim 45, wherein at least some of thelow-latency data that can affect the visualization of the user interfaceand at least some of the corresponding high-latency data that can affectthe visualization of the user interface is blended in a manner that isnot noticeable by a user.
 60. The system for processing user inputaccording to claim 45, configured to provide a low-latency systemresponse in a form that is dictated by application logic.
 61. The systemfor processing user input according to claim 60, wherein the form oflow-latency system response comprises a response or set of responsesselected from the group consisting of: an auditory response, a visualresponse, and a haptic response.
 62. The system for processing userinput according to claim 45, configured to provide a low-latency systemresponse in a form that is dictated by system logic.
 63. The system forprocessing user input according to claim 45, wherein the user inputdevice comprises a direct-touch input device employing at least one ofthe technologies selected from the group consisting of: resistive,direct illumination, frustrated total-internal reflection, diffuseillumination, projected capacitive, capacitive coupling, acoustic wave,and sensor-in-pixel.
 64. A system for processing user input, comprising:input device; input processing unit; high-latency subsystem comprisingsoftware running in a software stack; low-latency subsystem; inputprocessing unit software adapted to generate signals in response to userinputs; and, output device; wherein the low-latency subsystem processesthe signals with low latency relative to the high-latency subsystem andthe high-latency subsystem processes the user input events with highlatency relative to the low-latency subsystem; wherein the low-latencysubsystem receives the signals and generates at least one low-latencyoutput with low latency relative to the high-latency subsystem and thehigh-latency subsystem processes at least some of the signals andgenerates at least one high-latency output with high latency relative tothe low-latency subsystem; wherein the input device, the inputprocessing unit, the high-latency subsystem, the low-latency processingsubsystem, the input processing unit software and the output devicebeing arranged such that: the low-latency processing subsystem operatesindependently of and parallel to the high-latency processing subsystem;and at least some of the user input signals are processed by both thelow-latency subsystem and the high-latency subsystem, the low-latencysubsystem outputting to the output device a response to a given userinput signal with low-latency and the high-latency subsystem outputtingto the output device a response to the given user input signal withhigh-latency.
 65. The system for processing user input claimed in claim64, wherein high-latency data generated by the high-latency subsystem isgenerated by rendering.
 66. The system for processing user inputaccording to claim 64, wherein high-latency data generated by thehigh-latency subsystem and low-latency data generated by the low-latencysubsystem have substantially equal fidelity.
 67. The system forprocessing user input according to claim 64, wherein high-latency datagenerated by the high-latency subsystem and low-latency data generatedby the low-latency subsystem have unequal fidelity.
 68. The system forprocessing user input according to claim 64, wherein the high-latencysubsystem generates high-latency data and the low-latency subsystemgenerates low-latency data, and wherein at least some of thehigh-latency data is of higher fidelity than the correspondinglow-latency data.
 69. The system for processing user input according toclaim 64, wherein the low-latency subsystem is implemented, at least inpart, in at least one selected from the group of field-programmable gatearray (FPGA), application-specific integrated circuit (ASIC), amicrocontroller, a graphics processing unit (GPU), or a system on a chip(SoC).
 70. The system for processing user input according to claim 64,wherein the low-latency subsystem is implemented in logic integratedinto an existing component of a computing system.
 71. The system forprocessing user input according to claim 70, wherein the existingcomponent of the computing system comprises at least one selected fromthe group of a graphics processing unit (GPU), input device controller,central processing unit (CPU), microcontroller, or system on a chip(SoC).
 72. The system for processing user input according to claim 64,wherein the high-latency subsystem includes state information reflectingat least one state of the high-latency subsystem, and the low-latencysubsystem's response is dependent upon the state information.
 73. Thesystem for processing user input according to claim 64, wherein thelow-latency subsystem comprises user interface element logic.
 74. Thesystem for processing user input according to claim 73, furthercomprising: UI elements data containing data regarding the visualhierarchy and properties of visible UI elements; and wherein thelow-latency subsystem is adapted to perform hit testing based oninformation in the UI elements data.
 75. The system for processing userinput according to claim 64, wherein the low-latency subsystem isadapted to delete one or more of the signals from the stream, preventingsuch deleted signals from being part of the at least a portion of thestream of signals corresponding to at least some of the received datathat are received by the high-latency subsystem.
 76. The system forprocessing user input according to claim 64, wherein the at least aportion of the stream of signals corresponding to the high-latency datadiffer from the at least a portion of signals corresponding to thelow-latency data.
 77. The system for processing user input according toclaim 64, wherein a difference between at least some of the low-latencydata that can affect the visualization of the user interface andcorresponding high-latency data that can affect the visualization of theuser interface is perceptible to a user.
 78. The system for processinguser input according to claim 64, wherein at least some of thelow-latency data that can affect the visualization of the user interfaceand at least some of the corresponding high-latency data that can affectthe visualization of the user interface is blended in a manner that isnot noticeable by a user.
 79. The system for processing user inputaccording to claim 64, configured to provide a low-latency systemresponse in a form that is dictated by application logic.
 80. The systemfor processing user input according to claim 79, wherein the form oflow-latency system response comprises a response or set of responsesselected from the group consisting of: an auditory response, a visualresponse, and a haptic response.
 81. The system for processing userinput according to claim 64, configured to provide a low-latency systemresponse in a form that is dictated by system logic.
 82. The system forprocessing user input according to claim 64, wherein the user inputdevice comprises a direct-touch input device employing at least one ofthe technologies selected from the group consisting of: resistive,direct illumination, frustrated total-internal reflection, diffuseillumination, projected capacitive, capacitive coupling, acoustic wave,and sensor-in-pixel.
 83. A system for processing user input, comprising:input subsystem including an input device, the subsystem adapted tooutput signals in response to a plurality of user inputs to the inputdevice, the signals comprising information concerning the input;low-latency subsystem adapted to receive the signals and to generate alow-latency response in response to one or more of the signals, and tosend at least one of the signals to a high-latency subsystem; thehigh-latency subsystem adapted to receive the at least one of thesignals, and to generate a high-latency response in response to one ormore of the at least one of the signals; and, output device operativelyconnected to the low-latency subsystem and the high-latency subsystem,the output device configured to blend the low-latency response and thehigh latency response; wherein the low-latency subsystem generates thelow-latency response with low latency relative to the high-latencysubsystem and the high-latency subsystem generates the high-latencyresponse with high latency relative to the low-latency subsystem. 84.The system for processing user input claimed in claim 83, whereinhigh-latency data generated by the high-latency subsystem is generatedby rendering.
 85. The system for processing user input according toclaim 83, wherein high-latency data generated by the high-latencysubsystem and low-latency data generated by the low-latency subsystemhave substantially equal fidelity.
 86. The system for processing userinput according to claim 83, wherein high-latency data generated by thehigh-latency subsystem and low-latency data generated by the low-latencysubsystem have unequal fidelity.
 87. The system for processing userinput according to claim 83, wherein the high-latency subsystemgenerates high-latency data and the low-latency subsystem generateslow-latency data, and wherein at least some of the high-latency data isof higher fidelity than the corresponding low-latency data.
 88. Thesystem for processing user input according to claim 83, wherein thelow-latency subsystem is implemented, at least in part, in at least oneselected from the group of field-programmable gate array (FPGA),application-specific integrated circuit (ASIC), a microcontroller, agraphics processing unit (GPU), or a system on a chip (SoC).
 89. Thesystem for processing user input according to claim 83, whereinlow-latency subsystem is implemented in logic integrated into anexisting component of a computing system.
 90. The system for processinguser input according to claim 83, wherein the existing component of thecomputing system comprises at least one selected from the group of agraphics processing unit (GPU), input device controller, centralprocessing unit (CPU), microcontroller, or system on a chip (SoC). 91.The system for processing user input according to claim 83, wherein thehigh-latency subsystem includes state information reflecting at leastone state of the high-latency subsystem, and the low-latency subsystem'sresponse is dependent upon the state information.
 92. The system forprocessing user input according to claim 83, wherein the low-latencysubsystem comprises user interface element logic.
 93. The system forprocessing user input according to claim 92, further comprising: UIelements data containing data regarding the visual hierarchy andproperties of visible UI elements; and wherein the low-latency subsystemis adapted to perform hit testing based on information in the UIelements data.
 94. The system for processing user input according toclaim 83, wherein the low-latency subsystem is adapted to delete one ormore of the signals from the stream, preventing such deleted signalsfrom being part of the at least a portion of the stream of signalscorresponding to at least some of the received data that are received bythe low-latency subsystem.
 95. The system for processing user inputaccording to claim 83, wherein the at least a portion of the stream ofsignals corresponding to the high-latency data differ from the at leasta portion of signals corresponding to the low-latency data.
 96. Thesystem for processing user input according to claim 83, wherein adifference between at least some of the low-latency data that can affectthe visualization of the user interface and corresponding high-latencydata that can affect the visualization of the user interface isperceptible to a user.
 97. The system for processing user inputaccording to claim 83, wherein at least some of the low-latency datathat can affect the visualization of the user interface and at leastsome of the corresponding high-latency data that can affect thevisualization of the user interface is blended in a manner that is notnoticeable by a user.
 98. The system for processing user input accordingto claim 83, configured to provide a low-latency system response in aform that is dictated by application logic.
 99. The system forprocessing user input according to claim 98, wherein the form oflow-latency system response comprises a response or set of responsesselected from the group consisting of: an auditory response, a visualresponse, and a haptic response.
 100. The system for processing userinput according to claim 83, configured to provide a low-latency systemresponse in a form that is dictated by system logic.
 101. The system forprocessing user input according to claim 83, wherein the user inputdevice comprises a direct-touch input device employing at least one ofthe technologies selected from the group consisting of: resistive,direct illumination, frustrated total-internal reflection, diffuseillumination, projected capacitive, capacitive coupling, acoustic wave,and sensor-in-pixel.
 102. A system for processing user input with lowlatency, comprising: an input device; output device; an input processingunit; input processing unit software adapted to generate signals inresponse to user inputs; a high-latency response subsystem adapted tocreate a high-latency response to at least some of the signals; alow-latency response subsystem implemented at least partially inhardware, the low-latency response subsystem adapted to create alow-latency response to at least some of the signals, the low-latencyresponse subsystem comprising one or more parameters affecting thelow-latency response; wherein the low-latency response is not of higherlatency than the high-latency response, and the high-latency response isnot of lower latency than the low-latency response with respect tocommon signals; wherein the input device, output device, the inputprocessing unit, input processing unit software, the high-latencyresponse subsystem and the low-latency response subsystem are arrangedsuch that: the user input signals are processed in parallel by saidlow-latency subsystem and said high-latency subsystem; the output deviceoutputs the low-latency response and the high-latency response; andwherein application software can alter the one or more parametersaffecting the low-latency response.
 103. The system for processing userinput claimed in claim 102, wherein high-latency data generated by thehigh-latency subsystem is generated by rendering.
 104. The system forprocessing user input according to claim 102, wherein high-latency datagenerated by the high-latency subsystem and low-latency data generatedby the low-latency subsystem have substantially equal fidelity.
 105. Thesystem for processing user input according to claim 102, whereinhigh-latency data generated by the high-latency subsystem andlow-latency data generated by the low-latency subsystem have unequalfidelity.
 106. The system for processing user input according to claim102, wherein the high-latency subsystem generates high-latency data andthe low-latency subsystem generates low-latency data, and wherein atleast some of the high-latency data is of higher fidelity than thecorresponding low-latency data.
 107. The system for processing userinput according to claim 102, wherein the low-latency subsystem isimplemented, at least in part, in at least one selected from the groupof field-programmable gate array (FPGA), application-specific integratedcircuit (ASIC), a microcontroller, a graphics processing unit (GPU), ora system on a chip (SoC).
 108. The system for processing user inputaccording to claim 102, wherein the low-latency subsystem is implementedin logic integrated into an existing component of a computing system.109. The system for processing user input according to claim 102,wherein the existing component of the computing system comprises atleast one selected from the group of a graphics processing unit (GPU),input device controller, central processing unit (CPU), microcontroller,or system on a chip (SoC).
 110. The system for processing user inputaccording to claim 102, wherein the high-latency subsystem includesstate information reflecting at least one state of the high-latencysubsystem, and the low-latency subsystem's response is dependent uponthe state information.
 111. The system for processing user inputaccording to claim 102, wherein the low-latency subsystem comprises userinterface element logic.
 112. The system for processing user inputaccording to claim 111, further comprising: UI elements data containingdata regarding the visual hierarchy and properties of visible UIelements; and wherein the low-latency subsystem is adapted to performhit testing based on information in the UI elements data.
 113. Thesystem for processing user input according to claim 102, wherein thelow-latency subsystem is adapted to delete one or more of the signalsfrom the stream, preventing such deleted signals from being part of theat least a portion of the stream of signals corresponding to at leastsome of the received data that are received by the high-latencysubsystem.
 114. The system for processing user input according to claim102, wherein the at least a portion of the stream of signalscorresponding to the high-latency data differ from the at least aportion of signals corresponding to the low-latency data.
 115. Thesystem for processing user input according to claim 102, wherein adifference between at least some of the low-latency data that can affectthe visualization of the user interface and corresponding high-latencydata that can affect the visualization of the user interface isperceptible to a user.
 116. The system for processing user inputaccording to claim 102, wherein at least some of the low-latency datathat can affect the visualization of the user interface and at leastsome of the corresponding high-latency data that can affect thevisualization of the user interface is blended in a manner that is notnoticeable by a user.
 117. The system for processing user inputaccording to claim 102, configured to provide a low-latency systemresponse in a form that is dictated by application logic.
 118. Thesystem for processing user input according to claim 117, wherein theform of low-latency system response comprises a response or set ofresponses selected from the group consisting of: an auditory response, avisual response, and a haptic response.
 119. The system for processinguser input according to claim 102, configured to provide a low-latencysystem response in a form that is dictated by system logic.
 120. Thesystem for processing user input according to claim 102, wherein theuser input device comprises a direct-touch input device employing atleast one of the technologies selected from the group consisting of:resistive, direct illumination, frustrated total-internal reflection,diffuse illumination, projected capacitive, capacitive coupling,acoustic wave, and sensor-in-pixel.